Rotary explosive-engine.



UNITED STATES PATENT OFFICE.

JAMES A. MCLEAN, OF BOSTON, MASSACHUSETTS.

ROTARY EXPLOSlVE-ENGIN E.

SIEGLFIGATION forming part of Letters Patent No. 697,649, dated April 15,1902.

Application filed June '7, 1900. Serial No. 19,352. (No modell) To all whom, it may concern.-

Beit known that I, JAMES A. McLnAN, a subject of Victoria, Queen of Great Britain, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented a new and useful Engine or Transformer of Energy, of which the following is a specification, reference being had to the accompanying drawings.

My invention relates to gas and oil or vapor engines, and deals more particularly, with means of transforming the energy liberated in an engine-cylinder bythe burning and expansion of gas therein into rotary motion adapted for use for ordinary purposes of mechanical power. I aim especially to save and utilize a large proportion of such energy and expansive force, and thereby to make an engine or transformer of energy of very high efciency. It has long been known that hydrocarbon fluids contain in small compass relatively vast amounts of potential energy. The convenience with which such fuels can be burned within an engine-cylinder and the heat utilized directly, without the intervention of any storage device such as the steamboiler ordinarily required when coal is the fuel, has led many investigators and inventors to attempt to devise means by which this energy can be cheaply and efficient] y utilized. In some forms of gas and oil engines hitherto known it has been possible to attain a degree of efficiency that seems high when compared with the best efficiency obtained by the most' advanced steam-engine devices; yet no one before myself, I believe, has been able to approach the degree of efficiency which is theoretically possible. Countless attempts in this direction have been made by numerous inventors and by means of many devices during a period of many years. I have now accomplished this. It is done by the mechanism or system illustrated in the accompanying drawings, in Which- Figure l is a side elevation of my engine withpartsinsection,showingalso theair-tanks used in connection With it. Fig. 2 is an end elevation of the friction-clutch. Fig. 3 is-an enlarged sectional View showing in detail the valve mechanism. Y

No end elevation of the engine is necessary,

the parts being mostly cylindrical, and their arrangement and proportions easily obtainable froml the side View.

Referring to the drawings, I is the bed or framework of my engine, upon which are supported all the working parts, except certain Vtanks which may or may not at pleasure be incased in the framework.

2 is the explosion-cylinder. 3 is a piston traveling init, adapted to be driven outward by expansion of gas Within the cylinder.

4 is an ignition-tube inserted in the cylinder 2 at a little distance from the zero position of the piston.

5 is a connecting-rod running from the piston 3 to a rocker-beam 6. The beam 6 is supported at and swings upon a journal 7 in the engine-frame and is guided by the ways 8.

9 is a bridle-rod running from the rocker arm to the nut 10, which travels back and forth upon the screw 11. The screw is cut with a double thread to give strength. It is journaled in the engine-frame and is provided with a thrust-bearing, preferably a ballbearing, to withstand the thrust on the outward strokes of the piston 3. The nut is prevented from turning as it travels to and fro upon thescrew by the guide-rod l2, which passes through a slot I3 in the upper portion of the nut 10. A clutch consisting of the inner member 14 and the heavy rim 15 conveys Vthe rotary motion of the screw l1 to the drivin g-shaft 66. The clutch is of the well-known type which transmits motion in one direction only. The parts rotate without contact whenever the velocity of the inner member tends to be less than or in the opposite direction to that of the outer. The clutch shown has cylindrical rollers I7A in recesses on the outside of the inner member, said recesses being formed more shallow at one end than the other and of such depth that whenever the angular velocity of the rotating inner member is greater in the positive direction than the angular velocity of the rim surrounding it the rollers will be forced out against the rim, will make frictional contact therewith, and will impart the energy of the rotating inner member to the rim, yet will fall back into deeper portions of their respective recesses when the angular velocity of the inner member is less than or in contrary direction to that of the rim and allow the rim' and the in- ICO ner member to turn freely independently of one another. It will be obvious when the mode of operation of my engine is explained that any form of clutch which will accomplish the above result can be used in place of the form shown. On the driving-shaft 6G a fly-wheel 16 is mounted, from which a belt or gearing may connect with the machinery to be driven. I

1S is a rod joined at one end to the rockerbeam 6 and at the other end to the pistonrod 19, which is attached to the piston 20. The piston 2O travels in the cylinder 21. The end of this cylinder, which is approached by the piston 2O on the outward strokes of the explosion or combustion piston 3, is closed.

22 is an inlet in the cylinder 2l, located a short distance from and Within the limit of travel of the piston 20, corresponding to the outward limit of the combustion-piston, and is adapted to be closed by the piston 2O in Apassing by it. By this inlet the interior of the cylinder communicates freely through the pipe 23 with a small air-tank 24. In this tank 241 maintain a comparatively small pressure-I have found ten pounds above atmosphere suitable-supplying Whatever leakage or waste of airoccurs by means of apipe 25, in which is a reducing-valve 26, leadingfrom a main airtank 27. When my engine is in operation a relatively high pressure-I have found fifty to sixty pounds per square inch suitable-is maintained in the main tank 27 by the auxiliary pump 28. Any convenient means may be used to maintain this pressure, and in the drawings I have shown the pump as operated by a belt from the main shaft running over tight and loose pulleys 28 on the pump. To start the pump and fill the tank when the engine is not running, a hand-crank 2Sb is provided. A safety-valve 2Sc prevents the pressure in the tank 27 from rising too high. Whenever the inlet 22 is open, the piston 20 is therefore subject to a pressure of ten pounds per square inch, which is communicated by the connecting parts to the combustion-piston 3 and operates upon it in a direction opposed to the forces of expansion of the burned gases.

The valve mechanism is as follows: Admission is by the valve 29, which contains the passage or chamber 30 and which is normally held at the upper limit of its travel by the piston-plunger 3l, traveling in the cylinder 32 and communicating by means of the pipe 33 with the pressure in the small air-tank 24. The under surface of the nut 10 is formed as an inclined plane and is adapted to engage and depress a block 50, which is supported above the admission-valve 29 and communicates therewith through the medium of the cushioning-spring 65. When the admissionvalve 29 is at its lower limit of travel, the chamber 30 is opposite and forms a continuous passage, with the main air-supply passage 34 on one side and the admission-port 35 on the other side, thereby opening the port and permitting admission to the engine-cylinder of the contents of the chamber 33 and of air from the main supply-pipe 34. The latter communicates, 'through the pipe 36, with the main air-tank 27. When the admissionvalve 29 is at the upper limit of its travel, the admission-port is closed, and the chamber 30 is opposite the gas or vapor passage 37, the location of which is fixed by this requirement. This gas-passage consists of a small hole in the easement of the valve, so located as to open into the chamber 30 when the valve 29 is raised and the admission-port 35 closed. A short distance from its mouth the gas-passage is entered by a pipe 38, containing a check-valve, which pipe communicates with the source of supply of gasolene or whatever the fuel in use may be. Beyond where the pipe 38 enters the passage is a plunger-piston 39, which closes the passage and travels in and out within it under inliuence of the rockerarm 4l and the spring 40. The spring 40 tends to keep the plunger 39 normally Withdrawn at its outer limit of travel in the passage 37. In Figs. l and 3 it is shown at its inmostposition. WhenthenutlOapproaches its limit of travel corresponding to the inward position of the piston 3 in the combustion-cylinder, so that it is desired to prepare for a new explosion, the end of the nut strikes the roller 43 at the top of the lever or rocker 4l, thereby swinging inward its lower arm, which is so placed as to engage and push inward the plunger-piston 39. The rocker 4l is normally kept at its outward position by the spring 44, except when pushed in by the nut 10. These parts are so arranged that the rocker 4l will be pushed by the nut l0 shortly before the nut acts upon the block 50 to open theadmission-valve29. Theplunger39forces into the chamber 30 whatever charge of gasolene may be in the passage 37 at the time. Immediately afterward the admission-valve is depressed, thereby closing the mouth of the passage 37, opening the air-supply 34 and admission-port 35. The pressure of the airsupply forces air through the chamber 30, sweeping with it the contents of the chamber into the combustion-cylinder 2, thus admitting the explosive charge. The piston 3 begins to move outward, driven by the pressure of the charge. The nut 10 moves with it, thereby releasing iirst the block 50 and afterward the rocker 4l, whereby the admissionport is closed and the spring 40 is permitted to force outward the plunger-piston 39. This outward motion of the plunger sucks into the passage 37 through the pipe 38 the desired amount of gasolene which is to constitute the charge for the next explosion and which is on the return of the nut l0 for the next stroke forced into the chamber 30 and carried down with it as it descends to open the admissionport.

The exhaust-ports 5l are located at each end of the explosion-cylinder in the engine shown in the drawings. I do not, however, consider the port at the outer end of the cyl- IOO IIO

, movement ofthe rod by the pin 53.

inder absolutely necessary. The exhaustvalve 52 is operated by the guide-rod 12. This guide-rod is supported at lboth ends by the engine-frame, which it passes through at Yone end. A pin 53 passing through the rod and bearing against the engine-frame limits the rods motion in an outward direction. The rod is free to move inwardly except as its motion is restrained by the spring 54, strung upon it betweena collar 55 and the outside of the engine-frame. The motion of the guiderod inward operates by means of the rack and pinion 56 the rod 57, which controls the exhaust-valve 52. The guide-rodpasses through the upper portion of the reciprocating-nut 10. The nut 10 carries a piece of rawhide 58, fastened in the slot through which the guide-rod passes and adapted to bear upon' the surface of the guide-rod as the nut travels to and fro. By means of adjusting-screws 59 friction between the rawhide and guide-rod is regulated.

When the nut 10 travels outward, impelledA by explosion and expansion behind the piston 3, the friction between the rawhide and the guide-rod is preventedV from producing Whencver the nut 10 moves inward, corresponding to a return stroke of the piston 3, friction between the rawhide and the guide-rod pulls the rod inward slightly until balanced bythe spring 54, thereby opening the exhaust-valve.

So long as the nut is traveling inward this friction continues and the exhaust-valve remains open, except that at 60, near the inner end of the guide-rod, the surface thereof is cut away slightly, so lthat when the rawhide reaches this place, and when, therefore, the

piston 3 in its'corresponding travel has nearly reached the-inward end of its travel, friction between the nut and the guide-rod ceases.

The rod is then released, flies back under the influence of the spring 54, and the exhaustvalve is closed.

The governing is as follows: Upon the driving-shaft are carried the centrifugal balls 61, balanced and held by spring-arms 61fin the well-known method. The inner ends of the arms are fixed to the driving-shaft. The outer ends are carried in aiianged sleeve 62, which is free to slide in 'and out' on the shaft, according asthe balls are thrown out and in by increase and decrease vof angular velocity. A swinging rod 63, supported from the engineframe, engages with the circumferential groove between the flanges of the sleeve 62 and at its lower end is connect-ed with the rod 64,-the extreme end of which is located in the admission-valve casing and is in the-form of a bolt adaptedA to slide into the Valveway and catch the valve and prevent it from dropping when the inclined plane on thenut 10 depresses theblock 50. The motion of the block 50 is then taken up by the spring 65. When the main shaft is rotating at an excessive speed, the balls 61 are by centrifugal force thrown outward. The sleeve 62 travels inward. The rod 63 is thereby swung inward.

Its motion is multiplied by its own leverage, and the bolt end 64 thereof is pushed into the valveway, engages the admission-valve, and prevents it from falling. When the parts are in this position, the admission-port cannot be opened. The chamber 30, containing the charge of explosive ready for the next explosion, remains closed. This state of things continues until the bolt 64 is withdrawn by decrease of speed of the shaft. The energy 0f the compressed spring 6'5 then opens the valve,l the nut 10 being at its limit of travel.

The operation of the engine may now be understood. The opening of the admissionvalve 29 lets into the cylinder 2 a mixture of gas and air-under pressure from the main airtank of fifty or sixtypounds per square inch. Piston 3 is set in motion upon its outward stroke by this pressure. Its motion closes the admission-valve. The gases swirl around and become thoroughly mixed. The piston gathers headway and reaches the ignition-tube 4. Then explosion occurs and the piston is driven with great rapidity and force the remainder of its stroke. As it travels outward it carries with it the nut 10, which, as it cannot revolve, turns the screw rapidly upon its axis, and thereby drives the main shaft 66 through the medium of the clutch. The auxiliary piston 20 is likewise and at the same time driven into its cylinder. The various parts continue `in motion thus until the piston 20 passes and closes the inlet 22. Momentum of the parts keeps them moving and causes the piston to compress the air thus confined in the closed end of the cylinder 21, and thus a cushion is formed tending to resist rthe motion of the piston and 'the various moving parts connected to it. By thistime the pressure Vof gases in the explosion-cylinder has become much reduced by expansion. By their own momentum the parts are carried beyond the point where pressure in the cushioning-cylinder balances that in the combus'tioncylinder. The momentum is nally overcome and reversal of motion-takes place by/reason ofthe excess of pressure in the cushioning-cylinder 21. The motion of the nut in the opposite direction drags the guide-rod 1 2 and opens the exhaust mechanism, which releases whatever pressure remains in the combustion-cylinder and leaves the cushioning in the cylinder 21 in command. v Impelledby this Vcushioning pressure at first and afterward by the pressure in the small air-tank 24 when the piston has reopened the inlet 22 the parts move inward upon the return` stroke. The nut 10 now turns the screw 11 in the opposite direction, but does net retard the shaft 66 because of the intervening-clutch. This continues until the exhaust-valve is closed by the release of frictionon theguide-rod at depression 60. This release is timed by its location on the guide-rod so that a little compression will occur in the combustion-cylinder, thereby cushioning the inner end'of stroke before the block 50 opens 'the admission-valve for IOC IIO

the next stroke. As the nut 10 approaches the inward limit of its travel it strikes the block 50, opening the admission-valve 29, and admits air under pressure from the main airtank to the combustion-cylinder. The rush of air blows in with it the gasolene in the chamber 30. Impelled by its pressure the piston 3 and its connected parts start outward on a new cycle.

If the combustion mixture should fail to ignite, the momentum of the outward-moving piston will carry it beyond the point where the pressure in the cylinder 3 is balanced by the pressure on the cylinder 21. On swingingback the exhaust-valve will open, because the guide-rod is adapted to operate at whatever part of the stroke the main piston may reverse. It thus appears that at each explosion the shaft of the fly-wheel is given a forward impulse and that the reciprocating parts are automatically returned to their initial positions ready for a new explosion without in any way retarding the iiywheel. The purpose of the fly-wheel being to store energy and distribute it equally, it follows that in some cases the iy-wheel may be dispensed with or some other device for storing energy substituted. Thus if the engine be used for pumping air or water the shaft or the rim of the clutch may be coupled direct to the pump. So, also, the engine may be used to drive the propeller of a boat, in which case if a similar engine were coupled with it in multiple the alternate strokes of the engines would furnish continuous power without the need of a liy-wheel.

Many modifications of the mechanism specifically described and shown will suggest themselves to a skilled mechanic in order to adapt the engine to whatever particular work it may be required to do.

I do not restrict myself to the particular cycle of operations in the combustion-cylinder which occurs in the engine shown in the drawings. It is obvious that other cycles might be employed and other means of reciprocating the piston 3 without departing from the main feature of my invention, which resides in the combination of the screw and nut with other parts of the engine. I have shown and described the construction which I consider best. The screw may be made of any desired pitch and the cylinder 2 of any desired length relative to its diameter. The length of the cylinder should depend on the degree of expansion desired. It is possible by taking advantage of the momentum of the parts to carry the expansion to a point below atmospheric pressure. The length of stroke thus obtained, which is relatively great when compared with the length of stroke in ordinary types of gas-engines, enables a pitch to be adopted for the screw, so that the screw will make several revolutions per stroke. I have found that with a screw cut with a double thread for purposes of strength a suitable pitch is one giving one and one-half to two revolutions of the screw per stroke. The revolutions per stroke may be varied by varying the pitch or by changing the reducing motion between the piston 3 and the nut, as will be readily apparent to a mechanic.

I iind it best to so locate the inlet 22 in the cylinder 2l that the inlet willbe closed by the piston 20 and the motion of the main piston 3 arrested, thereby opening the exhaust at such a point that the expanded gases in the cylinder 3 will be a little above atmospheric pressure.

In gas-engines as ordinarily constructed, with a crank to transmute reciprocating motion into rotating motion,there is a great waste of heat. Much of the gas fails to unite with the oxygen mixed with it. Combustion continues throughout the stroke, and ame is even seen in the exhaust. This causes the offensive odor which has been a great objection to gasengines and is so common as to be considered a characteristic of gas-engines. Completelyburned gases have no odor. With my engine described in this specification perfect combustion ot' the entire chargeissecured, thereby utilizing a larger proportion of the energy ot' the fuel. l have discovered also that with my engine complete combustion occurs in a shorter time than in other forms of engines. I have further discovered that a larger proportion of the energy resident in the fuel and liberated bycombustion is actuallyconverted into mechanical energy than is the case in crank-engines. The proportion of heat which passes into the cylinder-walls and is radiated or absorbed by the jacket-water, and therefore not utilized, is very much smaller than in crank-engines. My engine not only has the advantage of securing complete expansion of the products of combustion from their highest pressure downto exhaust at atmospheric pressure, thereby utilizing to the utmost the temperature and pressure range, but it actually accomplishes this in less time per stroke than the crank-engine can do, for the reason that complete combustion and complete expansion occur at a more rapid rate than in the crank-engine. There are the further advantages that with my engine the impact upon the piston at the time of explosion is very small compared with the impact upon the piston of a crank-engine, because in my engine expansion begins immediately at a rapid rate; also, that the reciprocating parts do not run except when there is a demand for power. When the main driving-shaftis running at or above the desired speed, the governing mechanism stops the series of explosions and the main shaft meantime runs free and no more wear of reciprocating parts or consumption of fuel occurs until more poweris needed. Moreover, in crank-engines each impulse of the piston gives to the main driving-shaft but one-half a revolution. In my engine each impulse gives to the driving-shaft and iiywheel two revolutions. Furthcrm ore, the im- ICO pulses come at shorter intervals because of the relatively high speed of expansion in my engine. Energy stored in a rotating body varies with the square of the velocity. AIt follows that with my engine, in which the fly-Wheel rotates four times as rapidly as does the iiywheel of a crank-engine receiving impulses at the same rate, a iiy-Wheel of far less Weight and diameter is required to store the same amount of energy.

I claim- 1. In aninternal-combustion engine, a combustion-cylinder and a piston adapted to reciprocate therein; a screW-and-nut motiontransmuting device; means connecting the piston with the reciprocating member of the motion-transmuting device; means to return the reciprocating member of the motion-transmuting device to its initial position at the end of the stroke; a driving-shaft and a one-Way clutch connecting the rotating member of the motion-transmuting devicewith the drivingshaft. Y

2. In an internal-combustion engine, a combustion-cylinder and a piston adapted to reciprocate therein; a screw-and-nut motiontransmuting device; means connecting the piston with the reciprocating member of the t piston with the reciprocating member of the motiontransmuting device; a driving-shaft and a one-way clutch connecting the rotating member of themotion-transmuting device with the driving-shaft; an auxiliary motor 20, 21, connected with the combustion-piston; a compressed-air-storage tankl for the auxiliary motor; inlet 22 between that tank and vthe motor, all organized and arranged to cause the combustion-piston to be returned to its initial position by the operation of the auxiliary motor. JAMES A. MCLEAN.

Witnesses: K

Y OLIVER R. MITCHELL,

EVERETT E. KENT. 

